The present invention relates to a mine roof support having hydraulically operated consumers which include displacing cylinder-and-piston units and props, and to a control arrangement of the mine roof support.
Control arrangements for hydraulically operated mine roof supports are known in the art. In known arrangements, a hydraulically operated consumer of a mine roof support (for example, a prop, a return aggregate, or an adjusting unit) is operated directly from a neighboring mine roof support. For this purpose, flexible hoses serving as supply conduits and return conduits extend between a control unit or several control units on the neighboring mine roof support or between a main control valve arranged on the latter, and the several consumers. These hoses have an identical inner diameter for the purpose of standardization and simplicity of mounting and are connected to a consumer whose operation requires a large amount of medium per time unit. Since the latter mentioned consumers are utilized in a smaller number than the consumers with a smaller amount of medium required per time unit, this means that about four fifth of the supply and return conduits are overdimensioned. Therefore, the expenditures for not functionally justified hose conduits are high. It is not only unnecessary to utilize a great number of hose conduits with a larger inner diameter, but correspondingly dimensioned hose joints and main control valves must be utilized in such a construction, which also involves unnecessary expenditures. These expenditures are further increased since in many cases throttles must be incorporated in the hose conduits which lead to consumers with only small amount of medium required per time unit.
Side by side with these operationally determined shortcomings, the known control arrangement has a further disadvantage that a large space between the neighboring mine roof supports is occupied by a plurality of hoses with a large inner diameter. This hinders miners working in the mine and makes difficult the displacement of the mine roof support, especially in the conditions of low strata. Moreover, the great number of hoses in connection with the great space consumption results in raised danger by stonefall and increased risk of damages.
In order to eliminate a part of these short-comings, it has been proposed to transfer the main control valves for the consumers from the neighboring mine roof support to the main mine roof support and to provide only here the connecting conduits between the main control valves and the consumers, and therefore the hoses with a larger inner diameter. However, in this case again the hoses, for the purpose of the standardization and simple mounting, have a diameter which is determined by the consumer which requires the largest amount of medium per time unit. Due to the placing of the main control valves on the main mine roof support the conduits between the neighboring mine roof support and the main control valves on the main mine roof may have smaller inner diameter so that only one clustered strand lies between the mine roof supports. However, an additional pilot valve must be provided on the neighboring mine roof support, with the aid of which the main control valves on the main mine roof support can be actuated in a remote-control manner. At the same time, the main control valves which must match the hoses with a larger inner diameter are also expensive.